Lateral transfer of tetrahymanol-synthesizing genes has allowed multiple diverse eukaryote lineages to independently adapt to environments without oxygen

Takishita, Kiyotaka; Chikaraishi, Yoshito; Leger, Michelle M.; Kim, Eun-Soo; Yabuki, Akinori; Ohkouchi, Naohiko; Roger, Andrew J.

doi:10.1186/1745-6150-7-5

Cited by 48 publications

(68 citation statements)

References 23 publications

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“…For example, gammacerane (a breakdown product of the triterpenoid tetrahymenol) has been suggested to indicate the presence of ciliates (e.g., Tetrahymena) that produce tetrahymenol (Summons and Walter 1990). However, the gene responsible for tetrahymenol synthesis was shown to have been transferred between a wide range of microaerophilic eukaryotes (Takishita et al 2012).…”

Section: Calibrating Estimates Of Evolutionary Rates: Biomarkers and mentioning

confidence: 99%

On the Age of Eukaryotes: Evaluating Evidence from Fossils and Molecular Clocks

Eme

Sharpe

Brown

et al. 2014

Cold Spring Harbor Perspectives in Biology

223

155

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Our understanding of the phylogenetic relationships among eukaryotic lineages has improved dramatically over the few past decades thanks to the development of sophisticated phylogenetic methods and models of evolution, in combination with the increasing availability of sequence data for a variety of eukaryotic lineages. Concurrently, efforts have been made to infer the age of major evolutionary events along the tree of eukaryotes using fossilcalibrated molecular clock-based methods. Here, we review the progress and pitfalls in estimating the age of the last eukaryotic common ancestor (LECA) and major lineages. After reviewing previous attempts to date deep eukaryote divergences, we present the results of a Bayesian relaxed-molecular clock analysis of a large dataset (159 proteins, 85 taxa) using 19 fossil calibrations. We show that for major eukaryote groups estimated dates of divergence, as well as their credible intervals, are heavily influenced by the relaxed molecular clock models and methods used, and by the nature and treatment of fossil calibrations. Whereas the estimated age of LECA varied widely, ranging from 1007 (943-1102) Ma to 1898 (1655 -2094) Ma, all analyses suggested that the eukaryotic supergroups subsequently diverged rapidly (i.e., within 300 Ma of LECA). The extreme variability of these and previously published analyses preclude definitive conclusions regarding the age of major eukaryote clades at this time. As more reliable fossil data on eukaryotes from the Proterozoic become available and improvements are made in relaxed molecular clock modeling, we may be able to date the age of extant eukaryotes more precisely.

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Section: Calibrating Estimates Of Evolutionary Rates: Biomarkers and mentioning

confidence: 99%

On the Age of Eukaryotes: Evaluating Evidence from Fossils and Molecular Clocks

Eme

Sharpe

Brown

et al. 2014

Cold Spring Harbor Perspectives in Biology

223

155

View full text Add to dashboard Cite

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“…Tetrahymanol was first discovered in T. pyriformis (8) and has subsequently been detected in other eukaryotes including numerous marine and freshwater ciliates, an anaerobic free-living protist, an anaerobic rumen fungus, and a fern plant (9)(10)(11). Tetrahymanol has also been detected directly in freshwater and marine sediments (12,13), and it is recognized as a biological precursor of gammacerane (Fig.…”

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confidence: 99%

“…Further, the biochemical mechanism of tetrahymanol synthesis in bacteria is unclear. In ciliates, squalene-tetrahymanol cyclase (Stc) catalyzes the cyclization of squalene directly to tetrahymanol (24), but neither of the two known bacterial tetrahymanol producers harbor a copy of Stc (10,24). R. palustris and B. japonicum do possess an evolutionarily related cyclase, squalene-hopene cyclase (Shc), whose main function is the cyclization of squalene to the hopanoid diploptene (25).…”

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confidence: 99%

A distinct pathway for tetrahymanol synthesis in bacteria

Banta

Wei

Welander

2015

Proc. Natl. Acad. Sci. U.S.A.

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Tetrahymanol is a polycyclic triterpenoid lipid first discovered in the ciliate Tetrahymena pyriformis whose potential diagenetic product, gammacerane, is often used as a biomarker for water column stratification in ancient ecosystems. Bacteria are also a potential source of tetrahymanol, but neither the distribution of this lipid in extant bacteria nor the significance of bacterial tetrahymanol synthesis for interpreting gammacerane biosignatures is known. Here we couple comparative genomics with genetic and lipid analyses to link a protein of unknown function to tetrahymanol synthesis in bacteria. This tetrahymanol synthase (Ths) is found in a variety of bacterial genomes, including aerobic methanotrophs, nitrite-oxidizers, and sulfate-reducers, and in a subset of aquatic and terrestrial metagenomes. Thus, the potential to produce tetrahymanol is more widespread in the bacterial domain than previously thought. However, Ths is not encoded in any eukaryotic genomes, nor is it homologous to eukaryotic squalene-tetrahymanol cyclase, which catalyzes the cyclization of squalene directly to tetrahymanol. Rather, heterologous expression studies suggest that bacteria couple the cyclization of squalene to a hopene molecule by squalene-hopene cyclase with a subsequent Ths-dependent ring expansion to form tetrahymanol. Thus, bacteria and eukaryotes have evolved distinct biochemical mechanisms for producing tetrahymanol.gammacerane | tetrahymanol | biomarkers | methanotrophs | sterols

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“…Researchers agreed that the eukaryotic genome is a mosaic of archaea-related, bacteria-related and eukaryotic-specific genes. Genes from bacteria were transferred in the eukaryotic stem branch by EGT and HGT [20,34].…”

Section: Leca and The Hypoxic-oxidative Protolineagementioning

confidence: 99%

The evolutionary history of eukaryotes: how the ancestral proto-lineage conserved in hypoxic eukaryotes led to protist pathogenicity

Niculescu¹

2014

Microbiol Discov

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The aim and the background of this paper was to investigate how ancient primitive eukaryotes evolved to the successful parasites they are today. In preparing this work, the most significant literature of the last years has been studied. We expand it by the results of our own research. Results and conclusion: Anaerobic single-celled eukaryotes, such as Entamoeba invadens and Giardia lamblia, became successful invasive pathogens by using mechanisms inherited from the common ancestor (LECA). As described in previous papers pathogen protists have a surprising stem cell network (ancient protolineage) controlled by intrinsic and extrinsic mechanisms of cell conversion and differentiation inherited from the ancestor. Mechanisms leading to pathogenicity were not acquired after the organisms became parasitic, they were present before the single-celled organisms switched to parasitism. Only organisms possessing an extended ancestral stem cell system capable of switching between most oxidative (MO) and most hypoxic (MH) niches by changing metabolic pathways and antigenicity could develop into successful invasive pathogens like Entamoeba or Giardia. Related organisms not conserving all ancestral features evolved to become luminal commensals or free-living protists.

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Lateral transfer of tetrahymanol-synthesizing genes has allowed multiple diverse eukaryote lineages to independently adapt to environments without oxygen

Cited by 48 publications

References 23 publications

On the Age of Eukaryotes: Evaluating Evidence from Fossils and Molecular Clocks

On the Age of Eukaryotes: Evaluating Evidence from Fossils and Molecular Clocks

A distinct pathway for tetrahymanol synthesis in bacteria

The evolutionary history of eukaryotes: how the ancestral proto-lineage conserved in hypoxic eukaryotes led to protist pathogenicity

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